Variable power endoscope

ABSTRACT

An instrument for examining a relatively large area of the interior of a tube or other cavity in the human body in order to locate a lesion therein, and for then examining said lesion in greater detail without removing said instrument from said tube or other cavity. A variable magnification optical system is incorporated in said instrument sufficiently near its outward or proxal end so that the overall magnification of the instrument can be changed without removing it from said tube or other cavity.

United States Patent 3 Claims, 10 Drawing Figs.

11.8. CI 350/42, 128/7, 350/40, 350/49, 350/54 Int. Cl G02b 7/04, G02b7/ 10 Field of Search 350/40-44,

References Cited UNITED STATES PATENTS Lang Humbrecht Wappler WolfStrang Hett Littmann Primary ExaminerDavid Schoenberg AssistantExaminer-Toby H. Kusmer Attorney-Otto John Munz 350/42 X 350/42 350/54350/540 X 350/460 UX 350/54 X ABSTRACT: An instrument for examining arelatively large area ofthe interior of a tube or other cavity in thehuman body in order to locate a lesion therein, and for then examiningsaid lesion in greater detail without removing said instrument from saidtube or other cavity. A variable magnification optical system isincorporated in said instrument suffieiently near its outward or proxalend so that the overall magnification of the instrument can be changedwithout removing it from said tube or other cavity.

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VARIABLE rowan ENDOSCOPE BACKGROUND OF THE INVENTION The presentinvention relates to endoscopes, i.e., to the various kinds ofwell-known optical-medical instruments suitable for examining theinteriors of body cavities.

A wide variety of optical-medical instruments for the examination of theinternal organs of the human body are found in the prior art. All ofthese instruments must provide a solution to the common, basic designproblem, viz., that they must be adapted to transmit an image of thelesion or other object to be examined through a channel which is long ascompared to its diameter. This is accomplished in almost all of suchinstruments by means of a plurality of intermediate image-formingsystems which are disposed between the objective optical system locatedat the distal end of the instrument and the ocular optical systemlocated at the proxal end of the instrument. A prior art endoscope inwhich each image-forming system is a pair of lenses is shown in US. Pat.No. 1,680,490, issued to R. H. Wappler on Aug. 14, 1928. Anotherendoscope of the prior art is shown in U.S. Pat. No. 1,995,196, issuedto George Wolfon Mar. 19, 1935.

One disadvantage of the prior art endoscopes is that once the lesion orother object within the body had been located by means of an instrumentof relatively low magnification the finer details of the lesion or otherobject cannot be observed unless the low magnification instrument iswithdrawn from the body and a different instrument of higher magnifyingpower is inserted in its place. Obviously, this is extremely unpleasantfor the patient, especially when these instruments are inserted throughvery small body passages such as the urethra.

SUMMARY OF THE INVENTION In accordance with the present invention, thisdisadvantage of the known endoscopes is obviated by providing endoscopeswith optical systems of variable magnifying power which are located ator near the ocular end of these instruments and thus may be adjusted tovary the magnification while these instruments are in operating positionwithin the body of the patient. For this purpose, an endoscope accordingto the present invention may be provided with an ocular or eyepiece ofvariable magnifying power. According to another embodiment of thepresent invention, one of the intermediate image-forming systems,preferably the one located nearest the eyepiece, is replaced with asuitable optical system of variable magnifying power. When a variablepower ocular is used in carrying out the present invention, the fieldlens may be mounted for selective positioning in one of two differentpositions located on opposite sides of the ocular image plane, adifferent magnification corresponding to each of these positions.Mounting means for maintaining a lens in either of two selectedpositions are well known in the art. An ocular comprising a two-lenscombination of continuously variable magnifying power may also be usedin carrying out the present invention. As is well known in the art, themagnifying power of such a combination may be continuously varied bycorrespondingly continuously varying the spacing of the two lenses.

When the present invention is carried out by replacing one of saidintermediate image-forming systems with a lens system of variablemagnifying power, both of the lenses of the variable power lens systemwill be made displaceable.

When an endoscope according to the present invention is to be used inconjunction with photographic apparatus for recording or documentarypurposes, it is advisable to employ in such an endoscope, as themagnification varying element, either an ocular having two displaceablelenses, or a variable power lens system in place of one of saidintermediate imageforming systems, since in these arrangements themagnifying power can be changed without changing the position of theexit pupil. Some variable power optical systems which may be used toreplace one of said intermediate image-forming systems have more thantwo displaceable lenses.

It is therefore an object of the invention to provide an en- BRIEFDESCRIPTION OF THE DRAWINGS In the drawings: FIG. la represents theoptical system'of an endoscope embodying the present invention having adisplaceable ocular field lens wherein the ocular field lens ispositioned to produce one of the magnifying powers obtainable in thissystem;

FIG. lb represents the optical system of the ocular of the embodiment ofthe present invention shown in FIG. la when the ocular field lens is solocated as to produce the other magnifying power available in thissystem;

FIG. It represents the lenses of the ocular of FIGS. la and lb;

FIG. 2a represents the optical system 'of an endoscope embodying thepresent invention having an ocular of continuously variable magnifyingpower when the displaceable lenses of,the ocular are so positioned as toprovide one of the magnifying powers available with this system;

FIG. 2b represents the ocular portion of the optical system of FIG. 2awhen the displaceable lenses'of the ocular are so positioned as toprovide a value of magnifying power different from that provided whenthe displaceable lenses are positioned as shown in FIG. 2a;

FIG. 20 represents the lenses of the ocular of FIGS. Ia and FIG. 3arepresents the optical system of an endoscope embodying the presentinvention in which the intermediate image-forming system nearest theocular is of continuously variable magnifying power;

FIG. 317 represents the ocular of FIG. 30 when the displaceable lensesthereof are so adjusted as to provide a value of magnification differentfrom that provided when the displaceable lenses are positioned as shownin FIG. 3a;

FIG. 3c represents the ocular of FIG. 3a when the displaceable lensesthereof are so adjusted as to provide a value of magnification differentfrom that provide when the displaceable lenses are positioned as shownin FIGS. 3a and 312;

FIG. 3d represents the lenses of the variable-power intermediateimage-forming system of FIGS. 3a through 3:.

Several embodiments of the endoscope-of the present invention areillustrated in the accompanying drawings and the lenses of the variablepower elements'thereof are specified in the following tables. Themechanical details of endoscopes, and the nonvariable parts of theoptical systems thereof, are generally well-known in the prior art, asexemplified in U.S. Pat. Nos. 1,680,490, and 1,995,196, referred tohereinabove, and such mechanical details and nonvariable opticalelements will not be described or shown in detail herein. Only that partof the optical system of each embodiment which provides variablemagnifying power will be particularly described and specified in detailin the following tables.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1a and lb illustrate anendoscope optical system according to the present invention wherein theocular field lens is positionable in two different positions to providetwovalues of magnification. The optical data for variable power lenssystem of this embodiment are given in table I, the headings of whichrefer to the correspondingly designated elements of FIG. lc.As shown inFIGS. la and 1b, the reference character a designates the distancebetween the surface of the field lens nearest the objective and thevertex on the image side of the last member of the intermediateimage-forming systems. This system provides two different, predeterminedmagnifications which are related by the magnification factor 1.82.

FIGS. 2a and 2b illustrate an endoscope optical system according to thepresent invention wherein two optical elements of the ocular arecontinuously displaceable to correspondingly continuously vary themagnification of the svstem. The maenification factor relating to themagnifications available at the extremes of adjustment is 1.68. Theoptical data for the variable power lens system of this embodiment aregiven in table 2, the headings of which are referred to thecorrespondingly designated elements of FIG. 2c.

FIGS.3a through 30 illustrate an endoscope optical system according tothe present invention wherein the change in magnification is effected bydisplacement of two optical elements of the intermediate image-formingsystem located nearest the ocular. In this system the magnificationfactor relating the available magnifications at the extremes ofadjustment is 1.73. The optical data for the variable power lens systemof this embodiment of the invention are given in table 3,the headings ofwhich are referred to the correspondingly designated elements of of FIG.3d. As illustrated in FIGS. 3a through 30, a designates the distancebetween the vertex on the image side of the second member of theintermediate image-forming system nearest the ocular and theintermediate image plane.

' The mean values of the variable distances apply to a 1:1

Magnification factor 1.82.

m, is the distance of the surface of the field lens on the side of theobjective to the vertex on the image side of the last member of theintermediate imageproducing system.

sau-33324432 Magnification factor 1.73. I m; designates the:distancebetween the vertex on the image side of the second member of theintermediate image-producing system and the intermediate image plane.

The mean values of the variable distances apply to a 1:1 image.

It should be understood, of course, that the foregoing disclosurerelates to only preferred embodiments of the invention and that it isintended to cover all changes and modifications of the examples of theinvention herein chosen for the purposes of the disclosure, which do notconstitute departures from the spirit and scope of the invention setforth in the appended claims lclaim:

1. An endoscope including an intermediate image-forming optical systemand an ocular optical system, said ocular optical system having variablemagnifying power and being constructed according to the following tablewherein all linear dimensions are given in millimeters, r through rrepresent the successive radii of curvature of the surfaces of the lenselements, commencing with the lens surface nearest the intermediateimage-forming optical system, a, through a, representing the successivedistances between the vertices of the lens surfaces measured along theaxis of the ocular optical system, a, being the distance between theadjacent vertices of the most closely adjacent lenses of said systems, ndenotes the index of refraction of the glasses of the lens elements, andvreprescnts the Abbe number of the glasses of the lens elements, themagnifications of said ocular optical system being related by a factorof 1.82, and the focal length j varying between 14.9 and 27.1millimeters.

2. An endoscope including an intermediate image-forming optical systemand an ocular optical system, said ocular optical system having variablemagnifying power and being constructed according to the following tablewherein all linear dimensions are given in millimeters, r through rrepresent the successive radii of curvature of the surfaces of the lenseelements commencing with the lens surface nearest the interrnediateimage-forming optical system, a, through a represent the successivedistances between the vertices of the lens surfaces measured along theaxis of the ocular optical system, a being the distance between theadjacent vertices of the most closely adjacent lenses of said systems, ndenotes the index of retraction of the glasses of the lens elements, andv represents the Abbe number of the glasses of the lens elements theextreme magnifications of said ocular optical system being related by afactor of 1.68, and the focal lengthy varying between 9.86 and 16.53millimeters.

3. An endoscope including an intermediate image-forming optical systemand an ocular optical system, said intermediate image-forming opticalsystem comprising a variable power system constructed according to thefollowing table wherein all linear dimensions are given in millimeters,r, through r represent the successive radii of curvature of the surfacesof the lens elements commencing with the lens surface most remote fromthe eyepiece of the endoscope, a,, through a represent the successivedistances between the vertices of the lens surfaces measured along theaxis of the endoscope, a being the distance between the adjacentvertices of the lens of said variable magnifying power system which ismost remote from the eyepiece of the endoscope and the lens most closelyadjacent it, in the direction toward the objective, n denotes the indexof refraction of the glasses of the lens elements, and v represents theAbbe number of the glasses of the lens elements, the extrememagnification factors of said variable power optical system beingrelated by a factor of l.73.

1. An endoscope including an intermediate image-forming optical systemand an ocular optical system, said ocular optical system having variablemagnifying power and being constructed according to the following tablen v ao 38.4-21.5 r1 infinity a1 3 1.519 64.0 r2 -14.45 a2 10.75-27.65 r3+11.2 a33.8 1.610 59.2 r4 -13.13 a4 0.8 1.678 32.0 r5 infinity whereinall linear dimensions are given in millimeters, r1 through r5 representthe successive radii of curvature of the surfaces of the lens elements,commencing with the lens surface nearest the intermediate image-formingoptical system, ao through a4 representing the successive distancesbetween the vertices of the lens surfaces measured along the axis of theocular optical system, ao being the distance between the adjacentvertices of the most closely adjacent lenses of said systems, n denotesthe index of refraction of the glasses of the lens elements, and vrepresents the Abbe number of the glasses of the lens elements, themagnifications of said ocular optical system being related by a factorof 1.82, and the focal length f'' varying between 14.9 and 27.1millimeters.
 2. An endoscope including an intermediate image-formingoptical system and an ocular optical system, said ocular optical systemhaving variable magnifying power and being constructed according to thefollowing table n v ao 30.95-20.53 r1 -25.93 a1 1.5 1.519 64.0 r2Infinity a2 3.2-23.62 r3 Infinity a3 3 1.519 64.0 r4 -14.45 a416-6 r5+11.2 a5 3.8 1.610 59.2r6 -13.13 a6 0.81.67832.0 r7 Infinity wherein alllinear dimensions are given in millimeters, r1 through r7 represent thesuccessive radii of curvature of the surfaces of the lens elementscommencing with the lens surface nearest the inTermediate image-formingoptical system, ao through a6 represent the successive distances betweenthe vertices of the lens surfaces measured along the axis of the ocularoptical system, ao being the distance between the adjacent vertices ofthe most closely adjacent lenses of said systems, n denotes the index ofretraction of the glasses of the lens elements, and v represents theAbbe number of the glasses of the lens elements, the extrememagnifications of said ocular optical system being related by a factorof 1.68, and the focal length f'' varying between 9.86 and 16.53millimeters.
 3. An endoscope including an intermediate image-formingoptical system and an ocular optical system, said intermediateimage-forming optical system comprising a variable power systemconstructed according to the following table n v ao 12.66-31.66-56-66 r1+74.42a1 2 1.618 50.8 r2 -9.7 a2 1.21.734 28.1 r3 -22.65 a3 54-60-54 r422.65 a4 1.2 1.734 28.1 r5 +9.7 a5 2 1.618 50.8 r6 -74.42 ab58.32-33.32- 14.32 wherein all linear dimensions are given inmillimeters, r1 through r6 represent the successive radii of curvatureof the surfaces of the lens elements commencing with the lens surfacemost remote from the eyepiece of the endoscope, ao through ab representthe successive distances between the vertices of the lens surfacesmeasured along the axis of the endoscope, ao being the distance betweenthe adjacent vertices of the lens of said variable magnifying powersystem which is most remote from the eyepiece of the endoscope and thelens most closely adjacent it, in the direction toward the objective, ndenotes the index of refraction of the glasses of the lens elements, andv represents the Abbe number of the glasses of the lens elements, theextreme magnification factors of said variable power optical systembeing related by a factor of 1.73.